Virulence factors of the swine pathogen Actinobacillus pleuropneumoniae.

The Gram-negative bacterium Actinobacillus pleuropneumoniae is the etiologic agent of swine pleuropneumonia, a highly contagious respiratory infection with great economic implications. In recent years, considerable efforts have been invested in the study of its virulence mechanisms. Here we review the current knowledge on the determinants of A. pleuropneumoniae pathogenicity, paying particular attention to the capsule, the lypopolysaccharide, the outer membrane proteins, and the RTX exotoxins. The contribution of other factors is also discussed.